@dbtsai - one option would be to put a SPST 24 VAC relay and additional 24 VAC power supply in the system. Have Rachio fire the relay, which should have a low draw for its coil, and the connect the additional power supply through the relay to the motorized ball valve.
If you want to check that it is the ball valve causing the issue, then I’d do one of two test.
If there is a terminal with no valve connected to it, configure that zone as an active zone and then fire off a quick run, 5 minutes. If there is an error message, then the ball valve is pulling too much current. If all the terminals are in use, then one can remove the field wire for this test.
Run a quick run, say 5 minutes, on a zone that is not at the start of a schedule - in the event that the first zone being called is actually causing the problem. If there is not error, then run the first zone and see if you get an error message. If so, then it might be the first zone’s solenoid that is pulling too much current.
When there is a master valve in the system, Rachio has to guess if it is the master valve or the zone valve that is causing the problem.